A variety of commercial and industrial establishments emit air streams laden with VOCs and carbon monoxide that frequently are vented directly into the atmosphere with little or no treatment thereof prior to discharge from the source. However, federal, state and local environmental regulations now mandate that such air streams be treated to reduce the level of VOCs and carbon monoxide before the stream is emitted into the atmosphere.
One industry that is prone to the emission of VOCs and carbon monoxide is the wood industry. The manufacture of various wood products such as fiberboard, particleboard, plywood, wood pulp, etc., typically entails processing under elevated temperatures to achieve desired properties and characteristics for the wood products. The wood product selected for drying is often treated with chemicals, binders, varnishes, resins, adhesives, etc., prior to and during the process of drying. During the drying process, VOCs and carbon monoxide are emitted into the air stream used for the drying process and such pollutants must be removed or destroyed prior to discharge into the atmosphere.
In typical prior art processes, the air stream laden with the VOCs and carbon monoxide is treated in a regenerative catalytic oxidizer containing a catalyst that will reduce the level of such pollutants by oxidative conversion of the pollutants into water and carbon dioxide. Prior art catalysts include precious metal components such as platinum, palladium, rhodium, iridium and ruthenium; metal components such as vanadium copper, manganese, cerium and chromium as well as metal oxide catalysts such as manganese oxide or chromium oxide, and combinations of the foregoing metal and/or metal oxide catalysts.
Manganese-based, i.e., manganese-alumina, oxidation catalysts used for the oxidative destruction of VOCs and carbon monoxide are well known in the prior art. Such catalysts are relatively inexpensive in comparison to the metal catalyst mentioned above and exhibit a fair degree of activity in respect to the oxidative destruction of VOCs and carbon monoxide. A particularly useful manganese-alumina oxidation catalyst is that described in U.S. Pat. No. 5,880,059, which is incorporated by reference herein in its entirety. The manganese-alumina oxidation catalyst described in the '059 patent is available commercially and may be purchased from a source such as WRI Inc. or Elim A1 Industries, Inc. The catalyst described in the '059 patent exhibits excellent activity in respect to oxidative destruction of VOCs, but its activity in respect to the oxidative conversion of carbon monoxide to carbon dioxide is only fair.